There has been used a buckle for coupling and separating both ends of one string member or coupling and separating two string members.
The buckle includes a male member and a tubular female member. The male member is attached to one of members, which are to be coupled with each other. The female member is attached to the other member. The male member includes: a base; a pair of legs that respectively project from both widthwise sides of the base, the pair of legs being elastically deformable in a direction intersecting an insertion direction of the male member; and engaging portions that are respectively provided on the pair of legs, the engaging portions being engageable with the female member.
When the male member is inserted in the female member, the engaging portions on the pair of legs are engaged with the female member, thereby coupling the male member with the female member. In this state, when the pair of legs of the male member, which are exposed from the female member, are elastically deformed inward, the engaging portions on the pair of legs are disengaged from the female member, so that the male member can be separated from the female member.
In the above buckle, the pair of legs project from both the widthwise sides of the base of the male member. In a state where the male member is separated from the female member, the pair of legs may be likely to be accidentally caught by other objects, so that the pair of legs may be opened widely outward to be damaged. Further, when the male member is inserted into the female member with axes of the male member and the female member shifted from each other, either one of the legs may be positioned outside the female member. As the male member is further inserted, the leg may be opened widely outward to be damaged.
As an arrangement capable of solving these problems, for instance, buckles described in Patent Documents 1 to 3 are known.
In the buckles described in Patent Documents 1 and 2, a pair of legs respectively project from both widthwise sides of a base of a male member. Inside surfaces of distal ends of the pair of legs are coupled via a linking body in an inversed V-shape whose center projects toward the base.
In the buckle described in Patent Document 3, a pair of legs respectively project from both widthwise sides of a base of a male member and a guide bar projects from a widthwise center thereof. Central inside surfaces of the pair of legs are coupled via a linking body in a V-shape that extends around a distal end of the guide bar.    [Patent Document 1] JP-UM-A-61-86012    [Patent Document 1] Japanese Patent No. 3790094    [Patent Document 3] JP-A-2004-313268